#define _CRT_SECURE_NO_WARNINGS  1


struct ListNode* FindKthToTail(struct ListNode* pListHead, int k)
{
    if (pListHead == NULL)
    {
        return pListHead;
    }
    struct ListNode* fast, * slow;
    fast = slow = pListHead;
    while (k--)
    {
        if (fast == NULL)
        {
            return NULL;
        }
        fast = fast->next;
    }
    while (fast)
    {
        fast = fast->next;
        slow = slow->next;
    }
    return slow;
}